Electrode material of the invention is particularly suited for use in the aluminum industry. Such electrode material plays a role in the electrochemical process of producing aluminum and is needed in very large quantities. Each kilogram of aluminum requires about half a kilogram of electrode material, which can be used in the Soderberg furnace in the form of anode mass. Such Soderberg furnaces are equipped with continuous anodes, periodically coated with unburnt electrode briquettes. In this connection it is important to make sure that the basic material is produced in a way to have the proper grain size composition. The petroleum coke, which is precrushed, dried if necessary, ground, sifted and sorted out, will yield various coke fractions classified according to grain sizes and subsequently intermixed with bituminous coal tar pitch. The pitch plays the role of binding agent and fulfills the task of enveloping the coke particles and combine them to a pasty mass. The mass mixed and kneaded in this way, is imparted form at the outlet end of the mixing and kneading device, thus enabling the material to be cast in blocks or be formed into briquettes. The briquetted mass will then directly arrive to the continuous anodes of the Soderberg electrolytic furnace.
It has been already proposed to refrain from producing electrode material by the use of the classical, discontinuously operated so called trough mixer fitted with one or two agitator arms, but to use instead a mixing and kneading device that operates continuously, and which comprises a kneading worm member imparted a rotating motion as well as a reciprocating translatory motion. In such a case it is considered important to hold the operating conditions constant. This is a necessary condition for obtaining a uniform product. The pressure conditions prevailing in the mixing and kneading device are determined by the discharge cross-section provided at the outlet end of the system. The pressure conditions are generally changed by using nozzles and movable flaps, usually set manually by the operating personnel. Another solution known in the art provides for a discharge nozzle adjustable by means of a motor, and adapted to react to the pressure prevailing in the housing of a mixing and kneading device. However, the geometry of the completely kneaded mass is adversely affected by any changes in the cross-section of the nozzle provided at the outlet end of the mixing and kneading device.